Process for the recovery of rubber in plants by fermenting with clostridium



Patented Apr. 27, 1948 s PATENT OFFICE PROCESS FOR THE RECOVERY OF RUBBER UNITED s'rA'rr.

IN PLANTS BY FERMENTING WITH CLOS- TRIDIUM Secretary of Agriculture Application March 27, 1945, Serial No. 585,178

No Drawing.

13 Claims. (6!. 195-2) (Granted under the act of March 3, 18 83, as

amended April 30, 1928; 370 0. G. 757) i This application is made under the act of March 3, 1883, as amended by the act of April 30, 19-28, and the invention herein described, if patented, may be manufactured and used by or for the Govby mildmechanical action, such as shaking or stirring. l The separation of the released protoplasts containlng the rubber may be accomplished by screen ernment of the United States of America for goving the slurry. The protoplasts pass the screen ernmental purposes without the payment to us while the other leaf constituents are retained of any royalty thereon. on the screen. The protoplasts, which are heavier Rubber occurs in the leaves of certain plants than the liquid, settle out. It is desirable, but not in the form of globules 01' particles which are essential, that the pr t plasts be washed with l contained within the protoplasm of the chloroat by decanta-tion Centrifuge-731011 at this phyll bearing cells of the leaf. The protoplasm of stepy this pr a sep at on of a rubberthe cell is surrounded by the cell wall, a complex rich fraction is made, and the rubber can then structure containing cellulose, hemicellulose and be recovered fr t e pr t plasts. other constituents. This cell rubberis not re- O e ethod of recovering the rubber Present cover-able by tapping the latex system of the plant, in the protoplasts is by extraction Of the rubber if it contains such a system, nor is it recoverable from the dried p plasts with a suitable solvent by the well-known process of pebble milling the With Without the FY10r removalof y untreated tissue. It must be recovered by some extraction with acetone or related So vent. process which separates it from the proteinaceous Ou preferred method) of recovery p ises cell contents in which it is embedded. 20 the use of an alkaline solution, in the presence It is an object of our invention to recover this of an antioxidant, at elevated temp r to cell-rubber in good yield, dissolve or disperse the major portion of the non- In general, our invention comprises fermentarubber ns tuents of the protop sts. he retion of the leaves by organisms which digest the eased bbe bu es, e n ter than the Hocell walls, mild mechanical action to detach the an be recovered y allowing them to rise rubber-containing protoplasts from the plant and removing them from t Surface by Sk mdebris, separation of the protoplasts from the e. y subjecting t e a ne iquor to cendebris by screening, digestion of the protoplasts trifugal sep t The rubber can be Washed with alkali to release the rubber globules, and by dispe s g it in water and epeat t nseparation and recovery of the rubber as a latex. aration.

We have found that the cell wall can be digested The following e amp e s ates t e ma ner by certain microorganisms in such a manner that in w c ur invention may b a t ced: the protoplasts within them and the rubber which TWO hundred y grams of air-dried mp-- is in intimate mixture with the protoplasts can tostegia. grandiflom l e C ntaining 7.47 a s be released from the leaf either as a direct reof rubber were Suspended in 7 ite of Allison's suit of the fermentation or by mild mechanical me i m n fermented anaerobically by Glosaction, such as shaking or stirring. For example, iridium roseum for 6 y At the end of this if a suspension of leaves in water is incubated in m the slurry s i e vi orously for 30 the presence of Clostridium roseum-under condimmutes and Screened through a tions in which oxygen is essentially excluded, a 40 The material remaining o the screen was rapid fermentation takes place. This fermentai water rescreened' The two tion is characterized by an initial evolution of Hons -3 the screen. were combined and the gaseous pmducw The leaves are distended by protoplasts concentrated by centrifugation. The ti 1 th d th protopiasts were diluted to 700 cc. and 14 grams "F accumua mg W1 m an e of NaOH and mg. of hydroquinone monoep dermls may even separate completely from the benzyl ether, an antioxidant were added The vems and parenchyma" C(mcurrently, the cell suspension was heated to boiling and then cooled. W s Of the p y a are digested- At this Rapid cooling is preferred. The released rubber stage, the pr p st n inin th r r globules were recovered by centrlfugatlon and either fall out of the residuum or can be released 5Q skimming them from the surcface. They were Ca(OI-I)z are ineffective.

larger than the particles of Hevea latex.

then resuspended in water and acidied to pH 4 with acetic acid. The washed globules were copension of protoplasts for 15 minutes in 1.5%

NaOH solution gives essentially complete soluis helpful in following the progress of dissolution of the protoplasts.

The rubber from the alkaline suspension may be recovered by gravity creaming without added creaming agents. These particles are much In one instance, the weight average size was found to be 5.5 microns, and 75% to 85% of the rubber was recoverable by direct creaming. In other instances, the size of the globules has been found to vary with the age of the leaves and other factors. The recovery is as good or better when centrifugal separation is resorted to. The rubber tends to agglomerate in the centrifuge to a erably, the water is acidified to pH 3 to 4.7 with a suitable acid or buffer solution. Acetic acid is well suited for this purpose. In this pH range, the particles aggregate in a reversible manner and readily rise to the surface. We have also found that heating the suspension in this pH region produces an irreversible coagulation of the particles. This phenomenon may be used ,as a method of coagulation, and the product may then be dried in air or vacuum.

Various modifications of the procedure as described above fall within the scope of this invention. Aerobic fermentation with appropriate organisms also can be used to bring about the type of decomposition of the cell wall. Digestion of the cell walls may also be secured with other Boiling a sus- Clostridia, and any suitable antioxidants can be employed. The aqueous suspension of rubber particles obtained from this process can be further employed as a latex or treated by various methods common in rubber technology. Besides C'lostridium roseum, Clostridium felstntum has been used successfully in this process. Various suitable antioxidants, in addition to the two mentioned, are phenyl p-naphthylamine and trimethyl dihydroquinoline.

- Having thus described our invention, we claim: 1. The process of recovering rubber from Cryptostegia leaves comprising the combination fermentation by Clostridium roseum, permitting fermentation to proceed until the protoplasts containing the rubber globules are released from the cellulose part of the plant, then isolating the released protoplasts and boiling them in an aqueous alkali in the presence of a rubber antioxidant to elease the rubber globules and then recovering he rubber.

2. The process of recovering rubber from Cryptostegia leaves comprising ,the combination of steps wherein the leaves are first subjected to fermentation by a Clostridium organism, permitting fermentation to proceed until the protoplasts containing the rubber globules are released from the cellulose part of the plant, then isolating the released protoplasts and boiling them in an aqueous alkali in the presence of an organic rubber antioxidant to release the rubber globules and then recovering the rubber.

3. A process as defined by claim 2 in which the organism is Clostridium jelsinium.

4. A process as defined by claim 2 in which the antioxidant is hydroquinone monobenzyl ether.

5. A process as defined by claim 2 in whichthe antioxidant is 4.4'-diphenylphenylene.

6. The process of recovering rubber from Cryptostegia leaves comprising disintegrating the leaves by fermentation of a suflicient portion of the cellulose part of the leaves to result in a release of the protoplasts, separating the protoplasts from the plant debris, then boiling the separated protoplasts in an aqueous alkali, whereby the rubber globules are released from the proto-' plasts, inhibiting oxidation of the rubber during the bofling treatment, and then recovering the rubber.

'l. The process of recovering rubber from Cryptostegia leaves comprising disintegrating the leaves by fermentation of a sufllcient portion of the cellulose part of the leaves with a Clostridium organism to result in a release of the protoplasts, separating the protoplasts from the plant debris, then boiling the separated protoplasts in an aqueous alkali, whereby the rubber globules are released from the protoplasts, inhibiting oxidation of the rubber during the boiling treatment, and then recovering the rubber.

8. The process of extracting rubber from Cryptostegia leaves comprising decomposing portions of the cellulose part of the leaves by fermentation to release the rubber containing protoplasts, separating the protoplasts from the plant debris, dissolving the non-rubber constituents of the separated protoplasts by boiling them in an aqueous alkali solution, whereby rubber globules are released from the protoplasts, inhibiting oxidation of the rubber during the boiling treatment, and then recovering the rubber.

9. The process of extracting rubber from Cryptostegia leaves comprising decomposing portions of the cellulose part of the leaves by fermentation with a Clostridium organism to release the rubbercontaining protoplasts, separating the protoplasts from the plant debris, dissolving the non-rubber constituents of the separated protoplasts by boiling them in an aqueous alkali solution, whereby rubber globules are released from the protoplasts, inhibiting oxidation of the rubber during the boiling treatment, and then recovering the rubber.

10. A process as defined in claim 7 in which the organism is Clostridium roseum. 11. A process as defined by claim 7 in which the of steps wherein the leaves are first subjected $9 o g nism is Clostridium f lsmi m- 12. A process as defined by claim 9 in which the Number Name Date organism is Clostridium roseum. 1,753,185 Spence Apr. 1,, 1930 13. A process as defined by claim 9 in which the 1,918,671 Spence July 18, 1933 organism is Clostridium felsinium. 2,119,030 Spence May 31, 1938 JOSEPH NAGHSE. 5 2,365,950 Haefele et a1 Dec. 26, 1944 JONATHAN W2 WHITE, JR. THEE EFER SAMUEL 'R. HOOVER. o R ENCES Can. Jour. of Research, vol. 21-13, Oct. 1943. REFERENCES CITED Buchanan-Bacteriology, 4th Edit, The Mac- The following references are of record in the 10 m file of this patent: 1944 UNITED STATES PATENTS "India Rubber World" of May 1943.

Number Name Date 886,482 Dessan May 5, 1908 16 Spadaro, et a1., Rubber Age, page 53, October 

